Nonlocal van der Waals density functional made faster

TL;DR

This paper introduces a simplified and faster computational approach for the VV10 van der Waals density functional, enabling efficient calculations with maintained accuracy for molecular systems.

Contribution

It presents a new approximation and implementation that significantly speeds up VV10 functional computations using fast multipole methods and basis function fitting.

Findings

Achieves faster computation times for molecular systems.

Maintains the same accuracy level as the original VV10 functional.

Enables straightforward implementation with analytical integral evaluation.

Abstract

A simplification of the VV10 van der Waals density functional [J. Chem. Phys. 133, 244103 (2010)] is made by an approximation of the integrand of the six-dimentional integral in terms of a few products of three-dimensional density-like distributions and potential-like functions of the interelectronic distance only, opening the way for its straightforward computation by fast multipole methods. An even faster computational scheme for molecular systems is implemented where the density-like distributions are fitted by linear combinations of usual atom-centered basis functions of Gaussian type and the six-dimensional integral is then computed analytically, at a fraction of the overall cost of a typical calculation. The simplicity of the new approximation is commensurate with that of the original VV10 functional, and the same level of accuracy is seen in tests on molecules.